Magnetic core



April 3, 1951' E, D, TREAN 2,547,675

MAGNETIC CORE Filed Oct. 1, 1949 Invent 01": Edward D. Treanpr,

His Attornga.

Patented Apr. 3, 1951 UNITED STATES PATENT OFFICE General Electric Company,

New York a corporation of Application October 1, 1949-, Serial No. 119,149

3 Claims. 1

This invention relates to magnetic cores and, more particularly, to improvements in bent lamination type magnetic cores.

The term bent lamination is used in counterdistinction to the conventional flat-stack lamination type core. It i characterized by forming the core by bending its laminations. One Way of bending the laminations is to wind the core from a relatively long strip of magnetic material. Such wound. cores are sometimes subsequently cut at one or more places for facilitating their assembly with a conductive coil. Another way is to cut the laminations to the proper length from such a strip and then bend them to shape, usually after assemblying them into one or more packets of desired size. In either case, the laminations are usually fiatwise bent and the curvature is in the lengthwise dimension only. One of the problems connected with bent lamination type cores is the production of a tight, vibration-free joint having good magnetic properties at the places where the core has been cut for facilitating assembly with a conductive coil.

One object of my invention is to provide a new and improved magnetic core for induction apparatus including an improved core joint. A further object of my invention is to provide a new and improved method of joining bent lamination magnetic members to form a unitary magnetic core.

My invention consists essentially of a magnetic core structure including a joint which may be tightly closed by the use of members which protrude into keyways in the magnetic core adjacent to the joint and a structure whereby said members may be drawn together by the use of a wedge.

The invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the drawing, Fig. 1 shows the upper portion of a magnetic core having a joint and incorporating an embodiment of my invention; Fig. 2 is a similar view of a modification of my invention; Fig. 3 is a front view of a typical inductive apparatus incorporating a conductive coil and two of the magnetic cores of my invention; and Fig, 4 is a perspective view of the underside of one of the side plates which is used at the joints in my magnetic core.

Referring more particularly to Fig. 1, my core I with individual flatwise curved laminations 2 is separated at a joint 3 where there is a discontinuity in each of the curved laminations so that core ends 4 and 5 may be separated for the assembly of 'a conductive coil into the window space 6 enclosed by said core.

In the edges of each of the laminations at the core ends 4 and 5 two pairs of diametrically opposed rectangular slots or keyways l are out which are substantially parallel to the surfaces formed by the discontinuities in laminations 2 at joint 3. Into these keyways four keys 8 of rectangular section are respectively fitted, these keys being of a size and shape to snugly fit into and fill keyways l and to protrude from the keyways by a distance approximately equal to the depth of the keyways.

Side plates 9 and Iii, which are of a suitable insulating material, are held against the edges of laminations 2 over keys 8 at joint 3 by suitable wrap-around straps 1!. These side plates have depressions or keyways i2 and i3 on their inner sides next to the laminations to accommodate keys 1 while the side plates are held flat against the edges of the laminations. Keyways [2 are made in proper proportion to snugly accommodate the protruding portion of the associated keys 1. Keyways l3 have wedge-shaped portions which are not occupied by keys 1. These are shown more clearly in Fig. 4, which is a view of the inner side of side plate 9 before assembly. Wedges [4 are driven into these wedge-shaped portions of keyways I3 not occupied by keys LV and it will be seen that driving these wedges will draw adjacent keys 1 closer together through a tensioning in side plates 9 and I0, thereby drawing the core ends 4 and 5 very tightly together and closing joint 3. The material of plates 9 and I0 must be capable of withstanding these tension forces. These members may be alternatively of metal with suitable insulating sheets (not shown) to separate them from the core.

A suitable cement may be applied to the joint to fill any spaces which may remain and to make the joint quiet by eliminating any alternating current hum which might otherwise be present. The magnetic joint in my core is, therefore, positively closed with considerable force, and as a result the magnetic reluctance at the joint is reduced to a minimum.

Fig. 2 shows a modification of my invention in which means other than strap H are used to hold side plates 9 and I0 firmly against the sides of the core. This means consists of fiat tension members [5 of insulating material positioned between layers of the laminations 2 near the center section of the core. These tension members fit into suitable slots IS in side plates 9 and ID at which point studs I! are attached. Studs ll netic cores 2B of my invention with joints as above described at 2| and 22. I

Fig. 4 is a view of side plate 9 before assembly giving a more complete view of the slots or keyways i2 and i3 therein. Side plate in is similar Accordingly, while I have described and illustrated a preferred embodiment of my invention, I wish it to be understood that I do not intend to be restricted solely thereto but that I do intend to cover all modifications thereof which would be apparent to one skilled in the art and which come within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A magnetic core comprising flatwise curved laminations of magnetic strip material, a joint in said core for the separation of all of said laminations for the assembly of a coil upon said core, said core including slotted keyways on at least one side thereof adjacent to each side of said joint, keys for said keyways in assembled relation with and protruding from said keyways, a side plate, fastening means for rigidly attaching said side plate in assembled relationship with said side of said core, said side plate including keyways for the reception of the protruding portions of said keys, one of said side plate keyways including a Wedge-shaped portion on the opposite side of its cooperating key from said joint and a wedge within said wedge-shaped portion for tightly closing said joint.

2. A magnetic core comprising flatwise curved laminations of magnetic strip material, a joint in said core which may be opened for the assembly of conductive coils upon said core, said core having a pair of slotted keyways at each of opposite sides thereof at said joint, the separate keyways of each pair being on opposite sides of 4 said core joint, keys of greater cross-section than said keyways within said keyways and projecting therefrom, side plates of insulating material, wrap around straps for holding said side plates in position over each pair of said keys, said side plates having keyways therein for the accommodation of said keys, one of said keyways in each of said side plates having a wedge-shaped portion in addition to the portion occupied by said key on the side of said key away from said joint, and a wedge member within said wedge portion I for tightening said joint after all of said parts are in assembled relationship.

3. A magnetic core comprising fiatwise curved laminations Of magnetic strip material, a joint in said core which may be opened for the assembly of conductive coils upon said core, said core having keyways perpendicular to the planes of said laminations at said joint, a pair of said keyways being provided at each of opposite sides of said core, the separate keyways of each pair being respectively on opposite sides of said core joint, keys of greater cross-section than said keyways within said keyways and projecting therefrom, side plates of insulating material, flat tension members between core laminations adjacent to said joint for holding said side plates in place over each pair of said keys and keyways, said side plates having keyways therein for the accommodation of said keys, one of said keyways in each of said side plates having a wedge-shaped portion in addition to the portion occupied by said key on the side of said key away from said joint, and a wedge member within said wedge portion for tightening said joint after all of said parts are in assembled relationship.

EDWARD D. TREANOR.

Name Date Vienneau Aug. 2, 1949 Number 

